{"id":"CVE-2026-58226","state":"PUBLISHED","title":"Unauthenticated denial-of-service via unbounded HPACK integer decoding in hpax","description":"Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding.\n\nhpax decodes HPACK variable-length integers with no upper bound on the decoded value or the number of continuation octets. 'Elixir.HPAX.Types':decode_remaining_integer/3 accumulates the integer as int + (value <<< m), shifting by 7 more bits for each continuation octet and stopping only on a terminating octet or truncated input, never because the integer grew too large. Because BEAM integers are arbitrary precision, a run of N continuation octets builds an O(N)-bit bignum and re-adds into an ever-larger bignum on each step, so the total decoding cost is superlinear (about O(N^2)). An unauthenticated attacker who can send an HTTP/2 header block to a server using this decoder (reached through the 'Elixir.HPAX':decode/2 entry point) can supply a small header block that forces a large, attacker-controlled amount of CPU (and transient memory), a denial-of-service amplification.\n\nThis issue affects hpax from 0.1.1 before 1.0.4.","publishedAt":"2026-07-06T09:03:47.374Z","updatedAt":"2026-07-06T14:04:14.632Z","severity":{"score":8.7,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","source":"EEF"},"assigner":"EEF","products":["elixir-mint hpax"],"affected":[{"vendor":"elixir-mint","product":"hpax","packageName":"hpax","packageURL":"pkg:hex/hpax","defaultStatus":"unaffected","versions":[{"version":"0.1.1","status":"affected","lessThan":"1.0.4","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:elixir-mint:hpax:*:*:*:*:*:*:*:*"],"modules":["Elixir.HPAX","Elixir.HPAX.Types"],"programFiles":["lib/hpax.ex","lib/hpax/types.ex"],"programRoutines":[{"name":"'Elixir.HPAX':decode/2"},{"name":"'Elixir.HPAX.Types':decode_integer/2"},{"name":"'Elixir.HPAX.Types':decode_remaining_integer/3"}],"repo":"https://github.com/elixir-mint/hpax"},{"vendor":"elixir-mint","product":"hpax","packageName":"elixir-mint/hpax","packageURL":"pkg:github/elixir-mint/hpax","defaultStatus":"unaffected","versions":[{"version":"56db437a7e2c515e3bdd770ac7947b02cd2390d0","status":"affected","lessThan":"1ba4bb2dc91e80089cf89c73970ac3ded76f17eb","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:elixir-mint:hpax:*:*:*:*:*:*:*:*"],"modules":["Elixir.HPAX","Elixir.HPAX.Types"],"programFiles":["lib/hpax.ex","lib/hpax/types.ex"],"programRoutines":[{"name":"'Elixir.HPAX':decode/2"},{"name":"'Elixir.HPAX.Types':decode_integer/2"},{"name":"'Elixir.HPAX.Types':decode_remaining_integer/3"}],"repo":"https://github.com/elixir-mint/hpax"}],"references":["https://github.com/elixir-mint/hpax/security/advisories/GHSA-jj2p-32j7-whj2","https://cna.erlef.org/cves/CVE-2026-58226.html","https://osv.dev/vulnerability/EEF-CVE-2026-58226","https://github.com/elixir-mint/hpax/commit/1ba4bb2dc91e80089cf89c73970ac3ded76f17eb"],"weaknesses":["CWE-407"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/58xxx/CVE-2026-58226.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-58226","state":"PUBLISHED","datePublished":"2026-07-06T09:03:47.374Z","dateUpdated":"2026-07-06T14:04:14.632Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-06-29T18:54:08.633Z"},"containers":{"cna":{"title":"Unauthenticated denial-of-service via unbounded HPACK integer decoding in hpax","descriptions":[{"lang":"en","value":"Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding.\n\nhpax decodes HPACK variable-length integers with no upper bound on the decoded value or the number of continuation octets. 'Elixir.HPAX.Types':decode_remaining_integer/3 accumulates the integer as int + (value <<< m), shifting by 7 more bits for each continuation octet and stopping only on a terminating octet or truncated input, never because the integer grew too large. Because BEAM integers are arbitrary precision, a run of N continuation octets builds an O(N)-bit bignum and re-adds into an ever-larger bignum on each step, so the total decoding cost is superlinear (about O(N^2)). An unauthenticated attacker who can send an HTTP/2 header block to a server using this decoder (reached through the 'Elixir.HPAX':decode/2 entry point) can supply a small header block that forces a large, attacker-controlled amount of CPU (and transient memory), a denial-of-service amplification.\n\nThis issue affects hpax from 0.1.1 before 1.0.4."}],"affected":[{"vendor":"elixir-mint","product":"hpax","packageName":"hpax","packageURL":"pkg:hex/hpax","defaultStatus":"unaffected","versions":[{"version":"0.1.1","status":"affected","lessThan":"1.0.4","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:elixir-mint:hpax:*:*:*:*:*:*:*:*"],"modules":["Elixir.HPAX","Elixir.HPAX.Types"],"programFiles":["lib/hpax.ex","lib/hpax/types.ex"],"programRoutines":[{"name":"'Elixir.HPAX':decode/2"},{"name":"'Elixir.HPAX.Types':decode_integer/2"},{"name":"'Elixir.HPAX.Types':decode_remaining_integer/3"}],"repo":"https://github.com/elixir-mint/hpax"},{"vendor":"elixir-mint","product":"hpax","packageName":"elixir-mint/hpax","packageURL":"pkg:github/elixir-mint/hpax","defaultStatus":"unaffected","versions":[{"version":"56db437a7e2c515e3bdd770ac7947b02cd2390d0","status":"affected","lessThan":"1ba4bb2dc91e80089cf89c73970ac3ded76f17eb","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:elixir-mint:hpax:*:*:*:*:*:*:*:*"],"modules":["Elixir.HPAX","Elixir.HPAX.Types"],"programFiles":["lib/hpax.ex","lib/hpax/types.ex"],"programRoutines":[{"name":"'Elixir.HPAX':decode/2"},{"name":"'Elixir.HPAX.Types':decode_integer/2"},{"name":"'Elixir.HPAX.Types':decode_remaining_integer/3"}],"repo":"https://github.com/elixir-mint/hpax"}],"references":[{"url":"https://github.com/elixir-mint/hpax/security/advisories/GHSA-jj2p-32j7-whj2","tags":["vendor-advisory","related"]},{"url":"https://cna.erlef.org/cves/CVE-2026-58226.html","tags":["related"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-58226","tags":["related"]},{"url":"https://github.com/elixir-mint/hpax/commit/1ba4bb2dc91e80089cf89c73970ac3ded76f17eb","tags":["patch"]}],"metrics":[{"cvssV4_0":{"attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":8.7,"baseSeverity":"HIGH","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-407","description":"CWE-407 Inefficient Algorithmic Complexity","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-07-06T14:04:14.632Z"},"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:elixir-mint:hpax:*:*:*:*:*:*:*:*","versionEndExcluding":"1.0.4","versionStartIncluding":"0.1.1","vulnerable":true}],"negate":false,"operator":"AND"}],"operator":"OR"}],"credits":[{"lang":"en","type":"finder","value":"Peter Ullrich"},{"lang":"en","type":"remediation developer","value":"Andrea Leopardi"},{"lang":"en","type":"analyst","value":"Jonatan Männchen / EEF"},{"lang":"en","type":"analyst","value":"Eric Meadows-Jönsson"}],"impacts":[{"capecId":"CAPEC-130","descriptions":[{"lang":"en","value":"CAPEC-130 Excessive Allocation"}]}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/elixir-mint/hpax/security/advisories/GHSA-jj2p-32j7-whj2","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-06T12:49:38.954923Z","id":"CVE-2026-58226","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-06T12:49:52.028Z"}}]}}}